New Build Randomly Won't Post

[Mackerel Ice Cream]

My six hour old computer is having a lot of problems. At first, it wouldn’t post because of the RAM. Yellow LED DRAM indicator was on. Reseated each stick of memory and  then it finally booted. But now, sometimes it’s does not post completely posting. The computer beeps as it would normally do while booting, but then the CPU fans stop while the MB’s LEDs and RAM’s LEDs stay lit with no video and the keyboard is unresponsive. I have tried the following.

-Reseated PSU's cables from the GPU & MB. Booted into Windows, but on restart, failed to post completely
-Reseated RAM, Next bootup worked, but failed afterwards
-Reseated GPU, no change. I do not believe the GPU is the cause, because it came from a working computer.

-CPU temp's are around 42 without load. MB temp's are around 25, I think

 

I need to try the following.
-Reseating the PSU’s cable to the PSU itself
-MemTest? MB’s RAM reports returns without errors. Should I try another program other than MemTest? Does it still work in this day and age?

 

I think the problem here is bad RAM or MB. PSU seems fine as it is turning on every time.

Any suggestions? This is a head scratcher for me.

 

GTX 970 

3900x

D15

Corsair Vengeance 32gb

Tuf x570 plus

Seasonic 850x

[5x5]

Sounds like either the board is fubar or your +5VSB rail is going dark for no reason

[SpookyCitrus]

Have you tried re-seating the CPU and checking for any bent or broken pins?

[Mackerel Ice Cream]

6 minutes ago, 5x5 said:

Sounds like either the board is fubar or your +5VSB rail is going dark for no reason

I can try the other PSU connector. Too bad this isn't an easy fix.

3 minutes ago, SpookyCitrus said:

Have you tried re-seating the CPU and checking for any bent or broken pins?

I haven't tried reseating the CPU yet, but I did check the pins before I dropped it in. There was no resistance while installing the CPU though.

[5x5]

Just now, lowao said:

I can try the other PSU connector. Too bad this isn't an easy fix.

I haven't tried reseating the CPU yet, but I did check the pins before I dropped it in. There was no resistance while installing the CPU though.

You'd have to test a different power supply. Changing the cables won't so anything I'd the standby rail is shorted

[Mackerel Ice Cream]

4 minutes ago, 5x5 said:

You'd have to test a different power supply. Changing the cables won't so anything I'd the standby rail is shorted

That's like the one part I actually have extras of. I'll tested it and let you know. Thanks for the replies.

[Mackerel Ice Cream]

On 9/11/2019 at 1:51 PM, SpookyCitrus said:

Have you tried re-seating the CPU and checking for any bent or broken pins?

 

On 9/11/2019 at 1:59 PM, 5x5 said:

You'd have to test a different power supply. Changing the cables won't so anything I'd the standby rail is shorted

It looks like it was the PSU that was bad, because the replacement hasn't had any issues since it was replaced.  But right before I installed the backup PSU I couldn't get the computer to fail during post. Who know? However, thank you for replying and helping out.